I mean, all colors exist only in our brains. "Color" is a perceptual experience that may start as spectral power and cone excitation, but is then mapped to color sensation through a fantastically complex visual system in the brain. That's why color-based optical illusions work. That's why "The Dress" was controversial.
There's nothing that special about purple. The article makes a big deal about purple "connecting" two opposite ends of the spectrum, but this is just an artifact of humans seeing rainbows and realizing that pink-purple would connect the two ends, even if they're not present in the rainbow. It's just a human framework, not some kind of physical truth.
Put another way, there are a ton of colors that are not in the rainbow, because it's a 1D simplification of our color perception, which is 3D (three cones). Would you say brown "exists only in our brains?"
There's nothing that special about purple. The article makes a big deal about purple "connecting" two opposite ends of the spectrum, but this is just an artifact of humans seeing rainbows and realizing that pink-purple would connect the two ends, even if they're not present in the rainbow. It's just a human framework, not some kind of physical truth.
Put another way, there are a ton of colors that are not in the rainbow, because it's a 1D simplification of our color perception, which is 3D (three cones). Would you say brown "exists only in our brains?"